1. Field of the Invention
The present invention relates to the structure of an electronic device such as personal computers and word processors, and more specifically, to a liquid crystal display (LCD) device equipped with the electronic device and a method of manufacturing a reflection layer in the liquid crystal display device. The present invention may also be applied to an electro-optical device having the liquid crystal display device.
A “semiconductor device” as used herein refers to a general device activated by a semiconductor. Therefore, the above-noted liquid crystal display device and the electro-optical device also fall within a category of semiconductor device. For clarification, the terms of “liquid crystal display device” and “electro-optical device” are separately used herein.
2. Description of Related Arts
Typically, a reflection type liquid crystal display device is known. The reflection type liquid crystal display device is more advantageous than a transmission type liquid crystal display device in that a lower power consumption may be achieved since no back light is used. Incidentally, the reflection type liquid crystal display device has been increasingly required for a direct-vision type display for mobile computers and video cameras.
FIG. 11 is a schematic view showing an example of a conventional structure. Referring to FIG. 11, between a substrate 10 and an opposing substrate 17 are provided switching elements 11 such as thin film transistors, an interlayer insulating film 12, pixel electrodes 13, an orientated layer 14, a liquid crystal layer 15, another orientated layer 14, and an opposite electrode 16 in the stated order from the top surface of the substrate 10. Incident light 20 is reflected by the pixel electrodes 13 to generate a reflection light 21. It is to be noted that although all components are not shown in FIG. 11, which is a schematic view, a number of switching elements and a number of pixel electrodes are formed in a matrix on the surface of the substrate 10.
The reflection type liquid crystal display device utilizes an optical modulating action of the liquid crystal to select the state where the incident light is reflected by the pixel electrodes to be outputted to the outside of the device and the state where the incident light is not outputted to the outside of the device, thereby allowing for the light or dark indication, and a combination thereof would allow an image to be displayed. Each pixel electrode is made of a metal with a high refractive index such as aluminum, and is electrically connected to a switching element such as a thin film transistor.
Such an operational principle causes a phenomenon in which in such a displaying state as a light display, that is, the state where the incident light from the external is reflected by the pixel electrodes to be outputted to the external of the device, the display attained by reflecting the incident light by the pixel electrodes as it is, like a mirror, may glare or darken depending upon a viewing angle. In other words, there occurs a phenomenon that the angle of vision may be narrowed.
This is caused by the fact that the reflection state of the incident light differs depend on its viewing angle of the user. In order to avoid such a problem, a need arises to devise the incident light so as to be reflected diffusely on the pixel electrode.
In general, to obtain a diffused reflection, the surface of the pixel electrode made of a metal material is subjected to light etching to form a fine concave or convex portion thereon.
Hitherto, such a problem has been arisen in which the reflectivity of the refection layer is lowered due to the formation of an orientated layer with a high refractive index on the reflection layer (pixel electrodes made of a metal material). For example, in the case where an orientated layer (having the reflectivity of 1.6) is formed on a vapor-deposited aluminum layer (having the reflectivity of 91.6%), the reflectivity is lowered to 87.4% in calculation, or is lowered to approximately 85% to 86% according to an actual experiment.
In addition, conventionally, formation of a concave or convex portion on the reflection layer causes a reflectivity to be reduced in nature.
The conventional method of forming the reflection layer on which the concave or convex portion is formed by etching encountered a limitation in terms of the depth of the concave or convex portion to be made deep. Accordingly, there was a problem with the conventional reflection layer (pixel electrode) in terms of brightness applicable to a liquid crystal display device (particularly, to a direct viewing reflection-type liquid crystal panel), since the reflection and diffused reflection of light (including diffusion and scattering) were not sufficient.